1. Field of Invention
This invention relates to a motor vehicle lock with a latch, a ratchet which keeps the latch in a main catch, and an optionally present preliminary catch, and also having a closing aid, the closing aid having a drive—auxiliary closing drive—with a pivoting driving element and an auxiliary closing lever which is pivotably coupled to the driving element. The latch can be moved by means of the auxiliary closing drive via the driving element and via the auxiliary closing lever into a fully latched position—closing process—and for this purpose, the auxiliary closing lever can be coupled to the latch, and the closing process comprising a cycle of movements of the driving element. The motor vehicle lock is especially well suited to be a side door lock, but can also be used as a sliding door lock, rear door lock, rear hatch lock or a hood lock.
2. Description of Related Art
To increase ease of operation and to be able to reproducibly ensure an optimum closing process, motor vehicle locks are being increasingly equipped with an auxiliary closing function. The auxiliary closing function provides for the motor vehicle lock being transferred out of an intermediate position by a motor into the fully closed position. The intermediate position in a motor vehicle lock with a latch and ratchet corresponds generally to the half-latched position of the latch.
In a known motor vehicle lock (U.S. Pat. No. 5,516,164), to implement the auxiliary closing function, there are an auxiliary closing drive and an auxiliary closing lever in order to move the latch of the motor vehicle lock from the half-latched position into the fully latched position. In this closing process, the auxiliary closing lever engages a recess which is located on the latch, presses the latch into the fully latched position, and finally remains in a position in which the auxiliary closing lever blocks the resetting of the latch. Only when the ratchet is lifted, therefore when the motor vehicle door is to be opened, does the auxiliary closing lever disengage from the latch. The lifting of the auxiliary closing lever, therefore the decoupling of the auxiliary closing lever from the latch, is directly associated here with the lifting of the ratchet. This is implemented by an additional lever mechanism which requires high construction input.
Furthermore, a motor vehicle lock is known (U.S. Pat. No. 5,433,496) in which the ratchet itself is used as the auxiliary closing lever. Here, there is a lever mechanism which, on the one hand, enables movement of the latch into the fully latched position by means of the ratchet, and on the other hand, the raising of the ratchet itself. This design is complex and has disadvantages with respect to a flexible arrangement of the diverse parts in the motor vehicle lock.
The known motor vehicle lock underlying the invention (WO 03/071064 A1) is, likewise, equipped with a motorized closing aid. The closing aid has an auxiliary closing drive with a pivoting driving element and an auxiliary closing lever which is coupled with a pivoting capacity to the driving element. The auxiliary closing lever has a crank guide which can be engaged to an intermediate element. The crank guide thus causes guidance of the motion of the auxiliary closing lever such that the auxiliary closing lever is coupled to the latch at the start of the closing process and at the end of the closing process is decoupled from the latch.
In the motor vehicle lock which forms the starting point, the disadvantage is the fundamental fault susceptibility of the described crank guide. Here frictional losses or sticking can occur. Furthermore, it is disadvantageous that the components required here, especially the crank guide itself, are complex to fabricate. Finally it should be pointed out that basically the necessary coupling between the auxiliary closing lever and the intermediate element must be considered in the design; this leads to unwanted construction limitations.